Much of the focus of cancer research has been on the diagnosis and treatment of the condition. In recent years, because of advances in knowledge of biochemical processes at the cellular and subcellular levels, attention has been directed to methods, not only for diagnosing and treating cancer, but also for discovering a predisposition for cancer in the organism.
In these studies, "cancer suppression" was originally defined by a loss of tumorigenicity observed in fusion cells made with tumor cells and normal fibroblasts, lymphocytes or keratinocytes. The effect was presumed to be mediated by dominant suppressive factors in normal cells. Evidence indicated that these factors were in part genetic since a correlation existed between suppression of tumorogenicity and the presence of certain chromosomes in fused cells.
Another meaning for cancer suppressing genes arose in connection with genetic studies on certain childhood neoplasms and adult tumor syndromes. Genes contributing to the formation of these tumors appear to be oncogenic by loss of function, rather than activation, as with the classical oncogenes. Retinoblastoma, a childhood eye cancer, has provided the prototypic example. Refined cytogenic analysis and study of restriction fragment length polymorphisms (RFLPs) have suggested that retinoblastoma may result from a loss of a gene locus located in chromosome band 13q14. As referenced to the above referenced pending patent applications will disclose, significant advances have been made in the utilization of RB cDNA and RB protein not only in diagnosis and methods of treatment of RB-related tumors, but also in the elucidation of the cancer suppressor functions of other genes. Nevertheless, a significant need exists for appropriate methods for the therapeutic treatment of osteosarcoma, lung carcinoma, lymphomas and leukemias, which are not aminable to treatment by RB modalities.
In view of the above, it would be highly desirable to have a method for specific therapeutic treatment, independent of RB modalities, for osteosarcomas, lung carcinomas, lymphomas and leukemias. Further, it would be highly desirable to have such methods which could be used in conjunction with RB cDNA and protein product for the treatment of various tumors. Of course, it would be highly desirable to have such a therapeutic product which could be made in a purified state and which would be readily and effectively deliverable to a defective cell in a safe manner.